Electric separating filter



May 21, 1940. w. WILL ELECTRIC SEPARATING FILTER Filed\. Nov. 2, 1937 Patented May 21, 1940 PATENT orrlce ELECTRIC SEPARATING FILTER Walter Will, Berlin-Charlottenburg, Germany,

assignor to C. Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany, a company Application November 2, 1937, Serial No. 172,353 In Germany November 3, 1936 1 Claim. (01. 17844) The present invention relates to electric separating filters.

The wire-radio intelligence transmission over telephone and other networks by means of alternating high frequency carrier currents for broadcasting, alarm signaling and similar purposes is well known. Electric separating filters must thereby be provided which are adapted to separate the transmitted low frequency currents, for instance telephone speech currents, from the high frequency currents simultaneously transmitted over the network. It has been proposed to provide the inductances of such electric separating filters with shell-shaped high-frequency iron cores and to place said inductances on a shaft common thereto. It has also been proposed to assemble the inductances of the highfrequency filter portion on one shaft, and those of the low-frequency filter portion on a second shaft, and to combine these two assemblies together with the necessary condensers in one structural unit. Such type of separating filters having high-frequency and low-frequency portions is preferably employed in the subscribers stations in order to discriminate between the high-frequency and the low-frequency wire-radio currents.

The present invention has for its object to provide a particularly useful design for this type of electric separating filters.

According to the invention, all elements of the separating filter device are so mounted on a base plate, preferably of moulded insulating material, as to secure easy exchangeability of the individual elements and economical manufacturing of the filtering device as a whole.

The invention will be more readily understood from the following description in conjunction with the attached drawing, in which Fig. 1 shows a partially sectioned front elevation of one embodiment according to the invention, while Fig. 2 illustrates a section through the line 2-2 of the representation of Fig. 1.

Referring to the drawing,.a base plate I, preferably of moulded insulating material, carries terminal screws 2 which serve for establishing connections to the wire-radio lines as well as to the subscribers telephone sets. A box-shaped container 4, enclosing the condensers of the highfrequency and the low-frequency portions of the separating filter, is carried by a rib 3 of the base plate I. The base plate 5 of the container 4 is attached to the rib 3 by screws 6. The inductances 23, I3 and I4 of the low-frequency portion are placed on a spindle I common thereto, on which they are clamped together by a nut 24. The end of the spindle opposite to the nut 24 is formed to a stop head 21. The spindle is supported by arms 8 of the base plate I, preferably integral therewith. Each of the inductances 23, I3 and I 4 comprises a coil 9 (or 9a in the case of inductance 23), an inner cylinder III (or I Ila in the case of inductance 23), an outer cylinder II (or IIa for inductance 23) and two facing discs I2. The coil 9a of the inductance 23 is provided with two windings. The facing discs I2 as well as the cylinders I0, IDa, II and Ila, which together form shell-shaped cores, consist of high-frequency iron.

The inductance assembly of the high-frequency portion comprises one high-frequency transformer I5 and two inductances I6 and I1. These inductances I5, I6 and I1, and a number of the condensers enclosed in the container 4, are interconnected to a condenser circuit. Said inductances are mounted on a spindle I8 and formed similar to the inductances 23, I3 and I4 the principal difference being that their windings 9', 9' and 9a are designed for high frequencies. Their remaining structural members, therefore, are provided with the corresponding reference numerals I0, II, I2, Illa, Ila, I2 and 2I', the primed references Ila, I2 and 2| referring to members which have larger diameters than the members represented by the corresponding unprimed references Ila, I2 and 2|. Also the inductances I5, I6 and I1 are supported by arms 8 of the base plate I and clamped together on the spindle I8 by a nut 25. The end of the spindle I8 opposing said nut is provided with a stop head 28. Between the inductances 23, I3 and the inductances I'l, I5, or in any other suitable position an insulating plate or disc 2I is provided on each of the spindles and I8. Each disc 2! has soldering tabs 22, to which the leadin conductors are connected. A protecting cover I9 is attached to the base plate I, and may be slided thereto on a frame-shaped ledge, for example. The leads 28 inter-connecting the individual elements of the filter device are shown merely in the Fig. 2 for the sake of simplicity. For the same reason, also the cover I9 has been illustrated in the Fig. 2 only.

The electric separating filter above described is preferably used in the subscribers telephone equipment. The telephone set and one or more receiving apparatus adapted to receive the wireradio transmission are associated with the electric separating filter.

What is claimed is:

An electric separating filter of the type having a high-pass branch and a low-pass branch which comprises a plurality of high frequency inductances for said high-pass branch and a plurality of low frequency inductances for said low-pass branch, at least two of said inductances being mutually coupled together and at least two others of said inductances being substantially free from mutual coupling, a common shell-type core structure of high frequency iron linking through and surrounding said two mutually coupled inductances, individual shell-type core structures of high frequency iron linking through and surrounding each of said coupling-free inductances,

WALTER WILL. 

